Shift mechanism



Sept. 30, 1958 H. REICHLE 2,854,120

SHIFT MECHANISM Filed Dec. 29. 1954 IN V EN TOR.

HANS REICHLE I ATTORNEY sr-rrrr MECHANISM Hans Reichle, Mahopac Falls, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application December 29, 1954, Serial No. 478,339

1 Claim. (Cl. 197-74) This invention relates to typewriters and more particularly to an improved basket shift mechanism for controlling the upper and lower case printing of a typewriter.

In conventional typewriter construction, as more particularly described in U. S. Patent 2,517,989, Dodge, the typewriter basket, which holds the type bars in rest position, is shifted vertically to switch the printing point on a type bar from lower to upper case. This vertical shifting causes the type bars to bounce in the basket (as a result of their momentum) thus varying the distance between the type bar driving cam and power roll. If a type bar is operated during this bouncing period after the basket has been shifted, the printing impact force will be varied from its preset value, so as to vary the impression density of the printed character relative to other characters.

Accordingly, it is a first object of this invention to provide an improved basket shift device having harmonic motion so as to reduce the bounce of type bars during a shifting operation.

In the basket shift mechanism shown in the aforementioned patent, a great number of parts are involved thereby tending to make it a relatively expensive item, and accordingly, it is a further object of this invention to provide an improved yet less expensive basket shifting mechanism.

Also in the conventional typewriter, it has been found that a certain amount of maintenance is required to keep the basket shift operation adjusted, and therefore, it is a still further object of this invention to provide an improved basket shift mechanism which is relatively free from maintenance.

Other objects of the invention will be pointed out in the following description and claim and illustrated in the accompanying drawings, which disclose by way of example, the principle of the invention and the best mode, which has been contemplated of applying that principle.

In the drawings:

Fig. 1 is a perspective view of the improved basket shift mechanism shown in conjunction with a frame and power roll of an IBM typewriter.

Fig. 2 is an end view of the shift drive mechanism shown in Fig. 1; while Fig. 3 is an end view of the eccentrics shown in Fig. l.

Briefly, this invention relates to an improved basket shift device wherein a continuously rotating shaft is connected through a spring clutch and a gear system to an eccentric for moving the type basket from its lower to upper case position and return. The eccentric provides a harmonic motion, which is more economical to build, quieter in operation, helps the type bars to come to rest in a minimum time, and is relatively free from maintenance problems.

Referring to the drawings, a typewriter frame 2 is illustrated as supporting a continuously rotating power roll 4 for rotation in a counterclockwise direction under the control of belts 6, 7 and some motor source, not shown. An intermediate pulley 8 is mounted on, and, therefore,

ited States Patent 2. drives a shaft 10 which is supported in the typewriter frame in response to the driving of belts 6, 7.

The basket mechanism of a typewriter, as more particularly shown in the aforementioned Patent 2,517,989, is suspended by a plurality of parallel leaf springs 14, 16, 18, 20 for movement from its lower case to its upper case position and return. The leaf springs interconnect the basket support or frame 22 and the typewriter frame 2.

In order to drive the basket from lower case to upper case position, a pair of eccentrics 24, 26 are connected by means of connecting links 28, 30 respectively, to ears 32, 34, respectively, extending outwardly from the basket frame 22. Accordingly, as the eccentrics 24, 26 are rotated clockwise as shown in the drawings, through and assuming the high dwell is 180 displaced from the low dwell or rest position, as viewed in the drawing, then the eccentric acting through the connecting links will raise the basket frame 22 to its upper case position where it will stay until the eccentric makes another half revolution from its high dwell back to its low dwell or rest position, to return the basket to its lower case position.

The rotation of the eccentrics 24, 26, which are located on a shaft 25, is controlled by a gear 36 as driven by the pinion 38 which is connected by a spring clutch 40 to the continuously rotating shaft 10. More specifically, the gear 36 is pinned or otherwise secured to the shaft 25 for rotation therewith, and the pinion 38 is secured to a clutch housing 42 for rotation with a shaft 10 when the spring clutch 40 is engaged. The spring clutch 40 is a well known wrap around coil spring type. uni-directional operating member which interconnects the continuously rotating shaft 10 and the pinion 38 through the housing 42. With this structure, the shaft 10 will drive the pinion 38 so long as the coil spring in the: spring clutch tends to wind up, but as soon as any torque is applied to clutch 40 tending to unwind the clutch spring, then the shaft 10 may rotate relative to, and free from the pinion 38. To accomplish this operating relationship so that the clutch 40 is selectively operable, the clutch housing 42 is provided with an ear 44 positioned for engagement by a control bracket 48 in either of two 180 displaced positions. With this structure, so long as the control bracket 48 has one of its bent over portions or stops 50, 52 in engagement with the car 44, an unwinding torque is applied to the clutch 40 to release the same and thereby permit the shaft 10 to rotate free from the pinion 38. As soon as the control bracket 48 is pivoted clockwise about its support, which for convenience, in the disclosed embodiment is the shaft 25, the bent over portion 50 is removed from the path of ear 44 on the housing 42, whereupon the shaft 10 acting through the spring clutch 40 tends to rotate the housing counterclockwise as viewed in the drawing, thereby rotating pinion 38 counterclockwise and gear 36 clockwise so as to rotate the shaft 25. The rotation of the shaft 25 will drive the eccentric from the low dwell to its high dwell position thereby shifting the basket from its lower to its upper case position. The second stop 52 of the control bracket 48 is displaced 180 from its first stop 50, and accordingly, as the shoulder 44 rotates through 180, it will engage the stop 52. More specifically, the stops 50, 52 are parallel and spaced apart a distance only slightly greater than the diameter of the spring clutch housing 42 plus the radial distance of the car 44 extending beyond the housing 42. Accordingly, when the stop 50 has been raised out of engagement with the car 44, the stop 52 is positioned so as to block the ear 44 after it has made a 180 revolution. Through this operation, and with the pinion 38 and gear 36 having a 1:1 ratio, the eccentrics 24, 26 will have been rotated one half a revolution or 180 from their low dwell to their high dwell position, thereby moving the basket from its lower case to its upper case position.

When the ear 44 engages the torque will be applied to the clutch 40 tending to unwind the coil spring thereby disengaging the shaft 10 from ho 4 an he eniniqnfifiw y bas t will stay "in" its upper case position'unt il the stop 2 ;is

dropped outfofflthepath of the ear. 44, fWhen1thisitakes In; order to' place the operation of the control bracket 48 under the control of the kY lGl/ffililfQl'fbfiQifif shift operation, a pair of key levers 54,:55v are connected tog gether for parallel operation by a cross shaft-58 whichQin turn, is pivotally supported in the typewriter frame The depression ofieither the shift keys willrotate both with their cTossshaftSS about a pivotal'supporttmot shown),

The outer end: 60 of the keytlever 1' 54 is connected through a link fiz to thecontrol bracket 48'wherebytthe depression of either shift key 54 or 56 will rock the; outer end 60 clockwise with respect tothe piyot shaft 5 8.thereby raising a control bracket 48 so as to lift the stop 50 out of the path of earl44 permitting the spring clutch to make a half revolution until its operation is blocked by the interrengagement offthe ear 44 and the stop 52. So long as the shift keyis held in this depressedposition, thecontrol bracketr48 will remain in positionwith the armt52 blocking the rotation of spring 40through the' inter-engagement with the ear 44. Then when the operator releases the shift key, the outer end 60 will again be returned to its rest position through the action of a restoring spring 64. Therefore, the control bracket 48 is again moved to its Fig. 1 position so that the spring clutch will drive the pinion 38 through another half revolution until the ear 44 engages the stop 50 to returnthe parts tojthe position shown in Fig. 1.

stop 52, an unwinding The outer end of the key levers 54, 56 are supported in a well known guide comb 66, which controls the extent of their pivotal movement since the slots in the guide comb will block the movement of the key lever in either direction.

While there have been shown and described and pointed out the fundamental novel features of the invention, as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claim.

What is claimed is:

In a typewriter having a type basket mounted for shifting movement from a lower case to an upper case printing position and return, and a key lever, a mechanism for selectively shifting said basket under the con-t trol of said key lever from onelimitto another comprising a rotatable shaft, a pair of eccentrics coaxially mounted on said shaft, strap means interconnecting said eccentrics and said basket to provide for the positive shifting of said basket from one position to another as said eccentric shaft is rotated through a continuously rotating power source, driving means having a releasable clutch 'therein interconnecting said power source and said eccentric shaft, clutch control means for regulating the interconnection between said power source and said eccentric shaft to drive said eccentric shaft through 180 each time said clutch is actuated, and link means interconnecting said clutch control means and said key lever to provide'for the actuation of said clutch control means each time said key lever-is moved from one limit to another. A 7

References Cited in the file of this patent UNITED STATES PATENT S 2,275,759 Helmoud Mar. 19,1942 

